A intensity distribution of a light source can be measured by two types of method. In the first type, a sensor is put in a position away from the light source. The sensor is moved around a circumference of a circle with the light source at the circle center to measure a light intensity distribution. In the second type, a measuring device is put in a position away from the light source to measure the light intensity distribution. The measuring device includes an optical system with a CCD sensor and an ultra-wide-angle prism with a fisheye-like lens.
The sensor used in measuring a light intensity distribution can be classified into two types: photonic and thermal. A photonic sensor has high sensitivity and high response speed. However, the photonic sensor is expensive and cannot operate at room temperature. A thermal sensor is low-cost and can be operated at room temperature. However, the thermal sensor has low sensitivity and low response speed.